add legend after a loop

im bulding a program that finds the roots' the last number change from 0 to 20. after that im plot the result' and i want to add legend for each result. im probably getting complex numbers.

clear all;
close all;
Legend=cell(19,1)
for k=0:20
    p=[1 2 4 k]
    r=roots(p);
    figure(1)
    hold on;
    plot(r,'*')
    hold on;
    
    
end

axis ([-3.5 0.7, -3 3])
grid on;
plot( 0, [-3:0.01:3],'k.-')
hold off;
xlabel('Re(s)')
ylabel('Im(s)')
title('system poles with diffeent k')

Answer 1

[KSSV]

May be something like below:

figure(1)
hold on
for k=0:20
    p=[1 2 4 k] ;
    r=roots(p);
    
    plot(r,'*','DisplayName',num2str(k))
           
end

axis ([-3.5 0.7, -3 3])
grid on;
plot( 0, [-3:0.01:3],'k.-','DisplayName','out of loop')
hold off;
xlabel('Re(s)')
ylabel('Im(s)')
title('system poles with diffeent k')
legend show